Liverwort - General Characteristics, Life Cycle, Spore Dispersal, Evolution - Asexual reproduction
gemmae liverworts mosses species
The liverworts are one of three classes in the plant phylum Bryophyta. The other two classes are mosses and hornworts. Liverworts are small, green, terrestrial plants. They do not have true roots, stems, or leaves. Instead, they have an above ground leaf-like structure, known as a thallus, and an underground structure, known as a rhizoid. Most liverworts are found in moist environments and they tend to be less resistant to desiccation than their relatives, the mosses. Many liverwort species are found in temperate North America, but most species grow in the tropics.
Like mosses, many species of liverworts reproduce by making gemmae. Gemmae are small circular or spherical reproductive structures which are borne inside gemmae cups. The gemmae cups form on top of the thallus. Gemmae formation is an important form of asexual reproduction in many species of liverworts and mosses.
Additional Topics
Like mosses and higher plants, liverworts use chlorophyll-a, chlorophyll-b, and carotenoids as photosynthetic pigments and store their food reserves as starch. As in mosses and higher plants, their cell walls are composed of cellulose. Like mosses and hornworts, liverworts are restricted to moist environments for two principal reasons. First, they lack a vascular system for efficient transport of …
The general features of the liverwort life cycle are the same as in mosses. Both have a characteristic alternation of generations in which the multicellular diploid sporophyte is dependent on the green and "leafy" haploid gametophyte. As with mosses, the gametophyte of liverworts is the form most commonly seen in nature. In most species, a haploid liverwort spore germinates and gives…
There are only a few fossils of liverworts and mosses and there are no fossils of hornworts. This is because the soft tissue of these bryophytes does not fossilize well. The oldest known liverwort fossil is from the late Devonian period, about 350 million years ago. Most botanists believe that they originated long before this. Some botanists have proposed that there are over 10,000 species of live…
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User Comments
about 1 year ago
l am at present studing fossils plants and their present day relations and would be grateful if you could send any information on fossils liverworts to presentday liverworts and thier relations that you can pass on to me Thank you david smith